Process for the renovation of worn gun barrels and improvements in gun barrels



Patented July 12, 1927.

'E'ES} ATEN'l 05H.

PIERRE MALAVAL AND nnnn PAUL EUGENE PAQUELI R, 0 PARIS. FRANCE.

PROCESS FOR THE RENOVATION OF WORN GUN BARRELS AND IMPROVEMENTS IN v GUN BARBELS.

. No Drawing. Application filed In our prior U. S. Patent No. 1.5445469 there was described and illustrated a removable lining tube arrangement for gun barrels' according to which a worn liner could be removed and a new liner fitted into place without the gun barrel having to be returned to the workshop. this important result being due to the tact that a the liner was constructed of a metal having a very high elastic limit and. in any case. an elastic limit considerably higher than that of the metal forming the outer tube, the initial clearance provided between the liner and the tube, atter having been taken up at the moment of the passage of the projectile, restored immediately afterwards.

In the said prior patent formula: were given enabling the elastic limit to be possessed by the metal of the liner to be determined, so that it is considerably greater than that of the metal of the same composition of which the outer tube is formed. a

suitable clearance being allowed at the same time in order that the liners will not become permanently deformed when firing takes place, the immediate effect of which deformation would be to make them adhere to the metal of the tube and to malre it as a consequence impossible to extractthem without employing complicated tools.

It has been discovered that in practice it is possible, to a certain extent, to reduce the (litters-nee between the elastic limit of the metal ofthe gun barrel and that of the liner by compensating for this reduction in difference by a cold hardening. One of the most rational means for obtaining ll together a small increase in the elastic limit of the metal of the liner and this compensating cold ha "dening consists in subjecting a liner of ordinary gun steelto a selt-hooping operation.

Selt-hooping consists, as it is known, in producing a permanent deformation or set by internal hydraulic or other pressure; this pressure has the eitect of cold hardening the metal and raises by a notable extent the elastic limit. Further the special state produced by selt-hooping. which is comparable to the state of ordinary hooping, increases the elasticity of the liner and consequently assists in preserving the clearance between the liner and the gun barrel.

What We claim is:

1. A gun having an outer tube, an inner May 13, 1926, Serial No. 108,972, and in France August}; 1925.

of rest being less than the inner diameter of tube of ordinary gun steel cold-hardened and said outer tube to leave clearance therebetwee-n, whereby said inner tube may be easily removed. 7 V

3. In a gun having inner and outer tubes and having clearance between the outer and inner diameters respectively thereof, an inncr tube of the same material as said outer tube but strained beyond the elastic limit of said material and thereby having a. higher limit of elasticity than said outer tube.

5 In a gun having inner and outer tubes and having a clearance between the surfaces of said tubes in the state of rest whereby said inner tube may be readily withdrawn from said outer'tube, an inner tube ordinary gun metal having the metal thereof strained beyond its limit of elasticity and thereby adapted toexpand and be gripped by said outer tube under stress of tiring and to contract free of said'outer tube after firing.

5. A gun comprising an outer tube of normal gun meta-l an inner tube of gun metal normally having the same characteristics as the metal of said outer tube but strained beyond its elastic limit, the outer diameter of said inner tube being less than the inner diameter of said outer tube in the state of rest, the deformation imparted to the metal or" said inner tube permitting the latter to expand and be gripped by said outer tube under stressot firing and to contract tree of said outer tube after firing.

6. A liner for a gun, said liner being Selthooped to increase the elastic limit thereof, the outer diameter of said linerbeing less than the inner diameter of the gun.

In testimony whereof we have signed this specification.

PIERRE MALAvar. ENE PAUL EUGENEPAQUELIER. 

